Project Summary Alzheimer?s disease and related dementias are estimated to be among the most costly health conditions in America, with the bulk of the costs stemming from the provision of long-term services and supports: that is, help with everyday activities, such as bathing, dressing, grooming, using the toilet, eating, and moving around. Family and friends provide most of this care, often at great financial, emotional, and physical expense to themselves. This burden can be alleviated somewhat through a strong support system?a cohesive network of family and friends coordinating and communicating to provide support to both the caregiver and the care recipient?yet to date there is little research examining these support networks. This is surprising given that stronger networks are consistently associated with better health outcomes. And this may be particularly true for caregivers: because social networks change along with life transitions, caregiving potentially puts caregivers at risk of social isolation and worsened health. The handful of prior studies on this topic have significant limitations: namely, they focus on populations outside the U.S. or on older adults. This will be the first study to collect data on the social networks of family caregivers in a nationally representative online panel study of adults in the U.S., age 18 and over. Our aim is to identify family caregivers across the age spectrum to increase representativeness, measure extended perceived caregiver networks, and capture greater detail on caregiver network composition and structure (e.g. ?weak? ties, negative ties, frequency of contact, emotional closeness, or type of ties). We will examine common network typologies and their associations with a variety of measures of physical, mental, and social well-being, and we will test for potential mediating factors, including the caregiving context and care recipient health. Finally, we will examine change in caregivers? social networks and how it may be associated with caregiver health over the caregiving cycle. This work will help researchers and policymakers identify the network characteristics of caregivers that matter most for a variety of health and well-being outcomes over time. It is also a critical first step for collecting empirical data that can inform the development of caregiving interventions that incorporate social network-based interventions?for example, technology-based interventions that provide personalized network visualizations to trigger strategies for altering networks (e.g., dropping ties, connecting disconnected ties, or spending more time with supportive network members)?to improve the health and well-being not only of adults with dementia but also of their caregivers.